More than 1,300 immigrant minors were held for periods of three days or more in adult detention centers from 2008 to 2012, according to data released by an immigrant rights group Tuesday.

The data, obtained by the Chicago-based National Immigration Justice Center through a Freedom of Information Act request, raises questions about how children are being handled in a backlogged immigration detention and deportation system that has expelled undocumented immigrants at a record-setting pace since President Barack Obama took office.

Some 1,366 immigrant children were placed in adult jails, prisons and other facilities contracted for immigration detention. Of those minors, 371 spent more than three months locked up, while another 15 of them remained in detention for more than six months, the data show. Authorities put many of those youths and children into solitary confinement for their protection, according to McClatchy Newspapers.

“It’s a startling revelation” NIJC’s Executive Director Mary Meg McCarthy said in a press release. “The U.S. government has a responsibility to protect the wellbeing and human rights of all children in the immigration system,” she added.

ICE acknowledged that it is against the agency’s policy to allow unaccompanied minors to spend more than 72 hours in adult immigration detention in a statement forwarded to the Huffington Post.

“ICE takes the responsibility of caring for Unaccompanied Alien Children seriously,” the statement says. “Unaccompanied minors are carefully kept in staging facilities away from the general population and minors are only held in ICE custody when accompanied by their parents in a facility designed to house families.”

The total number of immigrant children detained in adult facilities is likely higher. The data provided to NIJC surveyed only 30 of the roughly 250 detention centers contracted by DHS to detain immigrants in deportation proceedings.

The Trump Administration has come under fire for its ‘inhumane’ Zero Tolerance policy at the border. Meanwhile, the Obama Administration not only didn’t follow the law but it also sent minors into prisons with other adults. These prisons could have housed Aliens that committed any crime.